Shale gas in the UK: it’s not all about the science

The gas is there, but companies in the UK need more support to get it.

Shale gas exploitation has recently been given the go-ahead in the UK. With all the excitement, claim and counter claim, it would be easy to forget that to date not a single molecule of methane from shale gas has been produced and sold. We have drilled one shale gas well. That’s an 8½ inch borehole in Lancashire, a little like pushing a pin through the ceiling of your living room and looking through the hole. It does not tell you much about what’s in there. So will this new source of gas make a difference?

Let’s start with some numbers. Present UK annual production of natural gas is around 1.5 TCF (trillion cubic feet), but each year we use about 3.3 TCF. In the USA in the last 10 years, approximately 20,000 shale gas wells have been drilled and they now have an annual shale gas production of 3-4 TCF per year. If we use the USA as an analogy, the UK would need to drill thousands of wells to prove the reserves exist and make up just a part of the annual 1.8 TCF short-fall. Unlike wind energy, where there has been a move to develop it offshore, this is ecomomically unviable for shale gas because the rate of flow of gas for each well (i.e. revenue) is low relative to gas from other types of rock . So we cannot get away from it - researching the risks and an open and honest debate about them is an essential element in gaining the social acceptance of the technology that will be required.

Durham University have been working on this. Firstly, despite what we are often told, to date in the USA there is not one proven case of contamination of drinking water due to fracking after hundreds of thousands of fracking operations. But the contamination question led us to establish a guideline for a safe vertical separation distance of 600m between the depth of the fracking and shallower water supplies. If adopted, contamination of water supplies would be extremely unlikely.

We’re working on other issues. For instance the water used for fracking flows back to the surface in a controlled way after the operation is over. This water is contaminated with naturally occurring radioactive material, otherwise known as NORM. Even with the hundreds to thousands of wells that would be required to make an impact in the UK, the amount of radionucleides such as radium 226, is going to be a fraction of that produced by the medical sector, universities and existing oil and gas production. It would need to be cleaned and any residue safely disposed of. The technology exists – so this is not a show-stopper.

USA shale gas production took off in the last 10 years because the country has thousands of onshore drilling rigs available to carry out the drilling and helpful landowners who in some cases own the gas under their land. Both are not the case in the UK. Even if the social acceptance is forthcoming, it will take years for the industry to gear-up to drill enough wells to make an impact on the production-consumption gap. The science behind extraction of the gas reserves may in the end be secondary to issues of public trust in oil and gas companies, regulators and local and national government. The gas is there, but companies in the UK need what was recently coined a "social licence to operate". Without this the wells will not be drilled and shale gas will only ever make a tiny contribution to our economy and energy security.

Richard Davies is director of Durham Energy Institute, one of Durham University’s eight Research Institutes

But does it really? Photograph: Getty Images

Richard Davies is Director of Durham Energy Institute.

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.